NGC3766 + NGC4945 + NGC5128

We finally had some clear nights and I was able to get the rig out and do some imaging. After spending so much time going after nebulae, it was a change of pace to aim for something a bit less dramatic. Not that a stellar cluster is any less dramatic, they’re a lot easier to image and process.

The data for all three images below was collected from my light-polluted back yard, and each image has been stacked and had it’s initial processing carried out in three different programs. Affinity Photo, Astro Pixel Processor and Siril v1.2.0b2. All images had their final post-processing completed with Affinity Photo.

It’s interesting to see the stark differences in the final output caused by these three different programs. I have tried to keep the post-processing (mostly) the same to really show these differences.

Going by the images here, I suspect I’ll keep using Siril for stellar clusters like this, and then rely on APP for “fun stuff” like nebulae and galaxies.

I keep seeing tutorials of people using Affinity to stack their images with great results, but I cannot duplicate their results. I have a feeling Affinity’s stacking algorithms are more aimed at monochrome + filter imagers and not for people using an OSC.

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NGC 3766 - Open Cluster in Centaurus (The Pearl Cluster)

NGC 3766 (also known as Caldwell 97) is an open star cluster in the southern constellation Centaurus. It is located in the vast star-forming region known as the Carina molecular cloud, and was discovered by Nicolas Louis de Lacaille during his astrometric survey in 1751–1752.

Image details:

• Gain: 100
• Offset: 10
• Temperature: 0 degrees C
• Exposure: 20 seconds
• Lights: 180
• Darks: 50
• Flats: 50
• Dark Flats (Bias): 50
• Stacked and pre-proc’d in Affinity/APP/SiriL, then processed in Affinity Photo

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NGC 4945 - Barred Spiral Galaxy in Centaurus

NGC 4945 (also known as Caldwell 83) is a barred spiral galaxy in the constellation Centaurus, visible near the star Xi Centauri. The galaxy was discovered by James Dunlop in 1826 and is thought to be similar to the Milky Way Galaxy, although X-ray observations show that NGC 4945 has an unusual energetic Seyfert 2 nucleus that might house a supermassive black hole. Around the nucleus of the galaxy, there is a dense disk of dust and gas, along with many dense star clusters.

I collected this data in 3 sessions with different settings.

Image details:

• Gain: 100 / 100 / 100
• Offset: 10 / 10 / 10
• Temperature: 0 degrees C
• Exposure: 20 /30 / 60 seconds
• Lights: 360 / 120 / 120
• Darks: 50
• Flats: 50
• Dark Flats (Bias): 50
• Stacked and pre-proc’d in Affinity/APP/SiriL, then processed in Affinity Photo

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NGC 5128 - Galaxy in Centaurus (Centaurus A)

Centaurus A (also known as NGC 5128 or Caldwell 77) is a galaxy in the constellation of Centaurus. It was discovered in 1826 by Scottish astronomer James Dunlop from his home in Parramatta, in New South Wales, Australia. There is considerable debate in the literature regarding the galaxy’s fundamental properties such as its Hubble type (lenticular galaxy or a giant elliptical galaxy) and distance (11–13 million light-years). NGC 5128 is one of the closest radio galaxies to Earth, so its active galactic nucleus has been extensively studied by professional astronomers. The galaxy is also the fifth-brightest in the sky, making it an ideal amateur astronomy target. It is only visible from the southern hemisphere and low northern latitudes.

The center of the galaxy contains a supermassive black hole with a mass of 55 million solar masses, which ejects a relativistic jet that is responsible for emissions in the X-ray and radio wavelengths. By taking radio observations of the jet separated by a decade, astronomers have determined that the inner parts of the jet are moving at about half of the speed of light. X-rays are produced farther out as the jet collides with surrounding gases, resulting in the creation of highly energetic particles. The X-ray jets of Centaurus A are thousands of light-years long, while the radio jets are over a million light-years long.

As in other starburst galaxies, a galactic collision is suspected to be responsible for an intense burst of star formation. Models have suggested that Centaurus A was a large elliptical galaxy that collided with a smaller spiral galaxy, with which it will eventually merge. For that reason, the galaxy has been of particular interest to astronomers for years. While collisions of spiral galaxies are relatively common, the effects of a collision between an elliptical and a spiral galaxy are not fully understood.

Image details:

• Gain: 100
• Offset: 10
• Temperature: 0 degrees C
• Exposure: 60 seconds
• Lights: 60
• Darks: 50
• Flats: 50
• Dark Flats (Bias): 50
• Stacked and pre-proc’d in Affinity/APP/SiriL, then processed in Affinity Photo

Note: Object information copied from Wikipedia. Their words, their copyright.

• Astro